The present invention relates to fluid stripping apparatus, and in particular apparatus for stripping rinse water from a vehicle in a car wash at low horsepower by directing air against the vehicle at high velocity and high pressure without the apparatus touching the vehicle's surface.
Using air to physically strip rinse water from a vehicle in a car wash is well-known. For example, U.S. Pat. Nos. 2,448,834, 3,903,562 and 4,161,801 all disclose apparatus for drying vehicles in a carwash by using forced air blown through a nozzle to strip water from the vehicle surfaces as opposed to evaporating the water. To physically strip rinse water from a vehicle, the air must be delivered at a sufficient pressure, velocity and volume. It is well known that the pressure, velocity and volume can be increased by bringing the air emitting nozzle close to the surface of the vehicle. By reducing the distance between the nozzle and the vehicle surface, the horsepower of the blower motors which force the air through the nozzle can be reduced. This, in turn, enables the drying apparatus to operate more quietly and at lower energy consumption.
In the limit, the nozzle actually touches the vehicle surface. For example, U.S. Pat. No. 2,448,834 discloses a motor vehicle drying apparatus with flexible T-shaped conduits which rest on the surface of a vehicle to be stripped of water. The T-shaped conduits have an elongated nozzle opening at one end for directing air against the surface of the vehicle. The air from the nozzles at the end of the T-shaped conduits "squeegees", or strips, the water from the vehicle.
U.S. Pat. No. 4,161,801 discloses another vehicle drying apparatus for stripping rinse water from a vehicle which uses flexible conduits having an elongated nozzle at one end. Like the nozzles in the flexible T-shaped conduits in U.S. Pat. No. 2,448,834, the nozzles in the flexible conduits in U.S. Pat. No. 4,161,801 ride on the surface of the vehicle to be dried and direct air against the vehicle surface to physically strip the water from the surface. The apparatuses disclosed in these patents both strip rinse water from a vehicle by placing an air-emitting nozzle right on the vehicle's surface to take advantage of the well-known property that the air velocity and pressure are greatest in the immediate vicinity of the nozzle.
These prior apparatuses, however, are not without their drawbacks. There is considerable reluctance on the part of many car wash customers to permit a nozzle to drag on the surface of their automobiles. In addition, vehicle dryers which use flexible conduits like those disclosed in U.S. Pat. Nos. 2,448,834 and 4,161,801 tend to have high maintenance costs because the flexible conduits are susceptible to tearing and the nozzles, because of repeated contact with vehicles, tend to break.
A better approach is to keep the nozzles off the surface of the vehicle entirely. This approach, of course, makes it necessary to project air with sufficient velocity, pressure and volume onto the surface to be stripped to achieve the desired "squeegee" effect.
Modern car washes typically are designed to handle on the order of 120 vehicles per hour, or approximately one vehicle every 30 seconds. To air-strip vehicles at such a rapid rate, contact velocities (i.e., the velocity of air striking the vehicle surface) of 8,000 to 10,000 feet per minute are necessary. Conventional strippers which do not physically touch the vehicles can achieve the necessary air contact velocities only by using high-horsepower blower motors. Such fluid strippers therefore consume large amounts of power and can be expensive to operate.
Moreover, even though these conventional strippers do not physically contact the vehicles, they must still get fairly close (2 to 3 inches) to the vehicle surface to effectively strip it of water. Since surface contours of an automobile change greatly along its length (e.g., from hood to roof to rear deck) and vary drastically from vehicle to vehicle, elaborate "follower" systems have been devised to enable the air nozzles of conventional systems to follow the vehicle contours and maintain a fixed distance between the nozzle opening and the changing contours of the vehicle surface. These "follower" strippers are complex and costly to manufacture and maintain.
A further disadvantage of conventional strippers is that conventional nozzles are inefficient, and are not properly designed to minimize velocity dissipation and jet divergence. This is one reason why "follower" strippers were developed. Conventional nozzles are incapable of delivering the required contact velocity except over very short distances. Prior attempts to minimize velocity dissipation and jet divergence utilized external flaps and deflectors on nozzles to influence the air flow external to the nozzle. This solution is self-defeating, since velocity dissipation and jet divergence result from energy loss of the air. Flaps or deflectors only serve to further rob the air of energy, thus actually increasing velocity dissipation and jet divergence.
It is an object of the present invention to provide a fluid stripping apparatus which projects air from a nozzle much further than conventional apparatus without appreciable loss of velocity to deliver a high-volume, high-pressure flow of air at low horsepower and which can strip fluids from a surface at a distance.
It is another object of the invention to provide a fluid stripping apparatus which minimizes velocity dissipation and jet divergence of air emitted from a nozzle without the need for external attachments.
It is another object of the invention to provide a fluid stripping apparatus which eliminates the need to "follow" vehicle contours in order to effectively strip the vehicle surfaces.
These and other objects and advantages of the invention will appear hereinafter.